The expression of the
glycosphingolipid antigens was investigated in human
colorectal carcinomas and adjacent normal tissues obtained by surgical operation from six patients. The
glycosphingolipids, including both non-acidic
glycolipid and
ganglioside, were extracted from the tissue specimens and separated by two-dimensional thin-layer chromatography of
silica gel. A novel neutral
glycolipid antigen migrating lower than Le(a)
blood group antigen was detected in the cancerous tissues of all six patients, but not in normal regions in the same patients. The structure of the
glycosphingolipid was partially characterized by gas chromatography and gas chromatography/mass spectrometry of
alditol acetate and negative ion fast atom bombardment mass spectrometry (FAB/MS) of the intact
glycolipid, and TLC-immunostaining with monoclonal anti-Le(a), -Le(b), -
sialyl Le(a), and -Le(Y) antibody, respectively. The novel neutral
glycosphingolipid in
colorectal cancer was identified to be the III(4)IV(2)Fuc(2)Lc(4)Cer,
Le(b) antigen of the human Lewis blood system. Direct FAB/MS showed the
ceramide was composed mainly of 2-hydroxy tetradecanon and C18
phytosphingosine. In such individuals, the expression of
Le(b) antigen in normal tissues is absent or minimal. Based on this study, we suggest that this
Le(b) antigen may be a human distal
colorectal cancer-associated
antigen, which will be helpful for diagnosis and treatment of distal
colorectal cancer.